GLASS AS 4386984 - Caterpillar

Illustration 1 g02177132
Schematic for the Cat Data Link
Illustration 2 g01672679
Terminal locations at the service tool connector
(A) +Battery
(B) −Battery
(C) CAN shield
(D) Cat Data Link +
(E) Cat Data Link −
(F) CAN data link −
(G) CAN data link +
Illustration 3 g01672676
Terminal locations at the P1 ECM connector that are for the data link
(P1-8) Cat Data Link +
(P1-9) Cat Data Link −
(P1-34) CAN data link −
(P1-42) CAN shield
(P1-48) +Battery (if applicable)
(P1-50) CAN data link +
(P1-52) +Battery (if applicable)
(P1-53) +Battery (if applicable)
(P1-61) −Battery (if applicable)
(P1-63) −Battery (if applicable)
(P1-65) −Battery (if applicable)
(P1-70) Keyswitch
Table 2
Troubleshooting Test Steps Values Results
1. Verify the Proper Installation of the Data Link Circuit
A. Disconnect the P1 ECM connector.
B. Measure the resistance between P1-50 and P1-34.
Data Link Circuit
Result: The resistance is between 57 ohms and 63 ohms and a -9 code is logged.
Repair: Check the power supply and ground to the module and all ECMs on the Can Data Link and the Cat Data Link that pertain to the -9 code that is logged or active. Power loss to any control module will generate a -9 code. Refer to the electrical schematic for details.
STOP
Result: The resistance is between 114 ohms and 126 ohms. A terminating resistor is missing.
Repair: Verify that two terminating resistors exist on the data link. One resistor must be located on each end of the data link. The engine is shipped with one terminating resistor that is installed between the ECM and the customer connector. Refer to the electrical schematic to determine the missing resistor. Replace the missing resistor and verify that the repair eliminates the problem.
STOP
Result: The resistance is less than 57 ohms.
Proceed to Test Step 2.
Result: The resistance is greater than 126 ohms.
Proceed to Test Step 3.
Table 3
Troubleshooting Test Steps Values Results
2. Check for a Short Circuit
A. Turn the keyswitch to the OFF position.
B. Thoroughly inspect the connectors that are associated with the data link circuits. Refer to Troubleshooting, "Electrical Connectors - Inspect".
C. Disconnect the P1 ECM connector.
D. Disconnect Cat ET from the service tool connector.
E. Remove the terminating resistors from the CAN Data Link circuit.
F. Disconnect the J1939 display if equipped.
G. Measure the resistance between the points that are listed in Table 4. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
Short Circuit
Result: The resistance is greater than 20,000 ohms.
Proceed to Test Step 3.
Result: The resistance is less than 20,000 ohms.
Repair: Repair the connectors and/or the wiring. Replace parts, if necessary.
STOP
Table 4
Resistance Measurements for the Cat Data Link
Connector and Terminal Terminal
P1-8 (Cat Data Link +) All of the other terminals on the P1 connector
Negative ground
P1-9 (Cat Data Link -) All of the other terminals on the P1 connector
Negative ground
P1-50 (CAN data link +) All of the other terminals on the P1 connector
Negative ground
P1-34 (CAN data link -) All of the other terminals on the P1 connector
Negative ground
Table 5
Troubleshooting Test Steps Values Results
3. Check for an Open Circuit
A. Fabricate a jumper wire that is long enough to create a test circuit across two terminals. Use the jumper wire in order to create a